European stocks close lower Monday

European stocks closed lower across the board on Monday.

The United Kingdom's FTSE 100 index dropped 0.28 percent to close at 10,720.30 points. France's CAC 40 index shed 0.66 percent to finish at 8,579.60 points. Germany's DAX index fell 0.38 percent to end the session at 26,338.61 points.

The U.S. National Highway Traffic Safety Administration (NHTSA) has opened an investigation into Tesla's certification that its new Cybercab meets all applicable Federal Motor Vehicle Safety Standards (FMVSS).

The probe, formally designated as an Audit Query, was opened on Sept. 3 and covers an estimated 1,000 Cybercab vehicles, according to an NHTSA investigation document made public on Friday. It will examine the process and technical data Tesla relied upon when certifying the Cybercab, as well as related issues. Tesla began commercial deployment of a small number of Cybercab vehicles in Austin, Texas, on Thursday and notified the agency that it had certified the vehicles as compliant with all applicable FMVSS. Tesla also told the NHTSA that it plans to gradually expand commercial deployment of the Cybercab to include additional vehicles and locations.

The vehicles lack permanently attached conventional manual controls, such as a brake pedal, gas pedal, steering wheel and mirrors, according to the NHTSA.

The agency said the inquiry will examine, among other issues, the extent to which Tesla's certification depended on determinations that certain FMVSS are inapplicable to the Cybercab.

In the United States, the NHTSA establishes vehicle performance requirements, while automakers must certify that their vehicles meet applicable standards before entering the U.S. market, subject to agency oversight to confirm compliance. The NHTSA said it conducts investigations when certified vehicles appear not to adhere to those requirements.